PMCCPMCCPMCC

Search tips
Search criteria 

Advanced

 
Logo of actaorthLink to Publisher's site
 
Acta Orthop. 2017 August; 88(4): 427–433.
Published online 2017 March 13. doi:  10.1080/17453674.2017.1304207
PMCID: PMC5499336

Poor relation between biomechanical and clinical studies for the proximal femoral locking compression plate

A systematic review

Abstract

Background and purpose

The proximal femur locking compression plate (PF-LCP) is a new concept in the treatment of hip fractures. When releasing new implants onto the market, biomechanical studies are conducted to evaluate performance of the implant. We investigated the relation between biomechanical and clinical studies on PF-LCP.

Methods

A systematic literature search of relevant biomechanical and clinical studies was conducted in PubMed on December 1, 2015. 7 biomechanical studies and 15 clinical studies were included.

Results

Even though the biomechanical studies showed equivalent or higher failure loads for femoral neck fracture, the clinical results were far worse, with a 37% complication rate. There were no biomechanical studies on pertrochanteric fractures. Biomechanical studies on subtrochanteric fractures showed that PF-LCP had a lower failure load than with proximal femoral nail, but higher than with angled blade plate. 4 clinical studies had complication rates less than 8% and 9 studies had complication rates between 15% and 53%.

Interpretation

There was no clear relation between biomechanical and clinical studies. Biomechanical studies are generally inherently different from clinical studies, as they examine the best possible theoretical use of the implant without considering the long-term outcome in a clinical setting. Properly designed clinical studies are mandatory when introducing new implants, and they cannot be replaced by biomechanical studies.

Efficacy and patient safety are key elements when new orthopedic implants are introduced on the market. This has been emphasized by Malchau in "On the stepwise introduction of new hip implant technology" (1995), consisting of 4 steps: the initial step with preclinical testing followed by 3 clinical steps including prospective randomized controlled trials, multicenter studies, and registry studies. Biomechanical studies are preclinical, and testing is aimed at reflecting the physiological situation with regard to efficacy of the mechanical fixation capability of the implant. They evaluate equivalency or improvement between the new implant and already established implants (Basso et al. 2012). Schemitsch et al. (2010) stressed the importance of biomechanical studies and suggested that studies could be ranked in the evidence hierarchy between expert opinion and clinical trials. However, biomechanical studies cannot reflect the clinical setting exactly. Malchau et al. (2011) referred to it as the "[.] inherent ‘gap’ between nonhuman supporting data and the unknowns of both efficacy and long-term safety in large human usage over many years [.]".

The "inherent gap" is especially interesting in the case of the locking compression plate (LCP) for the proximal femur (PF-LCP) (Figure 1), as biomechanical and clinical studies may not agree. An early prospective multicenter study on various fractures treated with LCP reported an 86% success rate (Sommer et al. 2003). The LCPs were supposed to be superior to the conventional fixation method in osteoporotic bone through better mechanical fixation of the implant to the bone (Wagner et al. 2004). The PF-LCP was then introduced for the treatment of proximal femoral fractures in 2007, with great expectations (Schmidt 2008)—as the first 3 biomechanical studies all showed PF-LCP to be stiffer and to have superior failure load compared to other implants (Aminian et al. 2007, Crist et al. 2009, Floyd et al. 2009). However, the first 2 clinical case-series showed complication rates of 29% and 70% (Wieser and Babst 2010, Glassner and Tejwani 2011).

Figure 1.
Locking compression plate used for treatment of a proximal femoral fracture.

This review explores the relation between the biomechanical and clinical studies for PF-LCP used in primary proximal femoral fractures, using a systematic approach for study retrieval. We chose PF-LCP for this review because it was introduced recently, with modern standards in both biomechanical and clinical trials.

Retrieval of studies

The searches were performed similarly to systematic reviews regarding the methods paragraph of the the PRISMA statement (Moher et al. 2010). Search strings were created in collaboration with a scientific librarian with expertise in systematic review.

The search string for biomechanical studies was as follows: ((biomechanical testing) OR (biomechanical research) OR (cadaver study) OR (biomechanical investigation) OR (in vitro) OR (biomechanical study) OR (biomechanical analysis) OR (biomechanical phenomena) OR (mechanical testing) OR (comparative analysis)) AND ((femoral neck fracture*) OR (fracture of the femoral neck) OR (hip fracture) OR (trochanteric fracture) OR (proximal femoral fracture) OR (intertrochanteric fracture) OR (subtrochanteric fracture)) AND (locking plate OR proximal femoral locking plate OR pflp OR LCP OR locking compression plate OR lc-dcp OR limited contact dynamic compression plate OR locking screw plate* OR (locked nail plate) OR pflcp OR pf-lcp OR proximal femur locking compression plate OR femur compression bone plate OR femoral neck locking plate OR FNLP).

The search string for clinical studies was as follows: clinical study OR comparison OR (case control) AND ((femoral neck fractures) OR (fracture of the femoral neck) OR (hip fracture) OR (trochanteric fracture) OR (proximal femoral fracture) OR (intertrochanteric fracture) OR (subtrochanteric fracture) OR (pertrochanteric fracture)) AND (locking plate OR proximal femoral locking plate OR pflp OR LCP OR locking compression plate OR lc-dcp OR limited contact dynamic compression plate OR locking screw plate* OR (locked nail plate) OR pflcp OR pf-lcp OR proximal femur locking compression plate OR femur compression bone plate)

The searches were conducted in PubMed on December 1, 2015. PF-LCP was introduced in 2007, and therefore 2007 was used as a time limit and all study designs were included. Language was limited to English or German, and animal studies were excluded. The following implants were excluded: implants resembling the PF-LCP, such as the Targon FN (Parker 2011), distal femur LCP used proximally, or LCP used in periprosthetic fracture management. Revision of earlier operations and pathologic fracture (other than osteoporosis) management were also excluded.

The searches yielded 124 biomechanical and 148 clinical studies. 2 reviewers screened the studies by title, then by abstract, and finally by reading the full text. The final list with included studies was compared and disagreement was solved through discussion between the 2 reviewers. To ensure literature saturation, reference lists of included studies or relevant reviews identified through the search were scanned, and 2 further clinical studies were found. 7 biomechanical studies (Table 1) and 15 clinical studies (Table 2) met the inclusion and exclusion criteria.

Table 1
Biomechanical studies with locking plates for proximal femoral fractures (PF-LCP)
Table 2
Clinical studies with locking plates for proximal femoral fractures. Complications in percentage of number (n) at follow-up

One reviewer extracted data from the studies, and discussion of relevant data was done by all authors. A second reviewer cross-checked all the data in Tables 1 and and22.

Femoral neck fractures were defined as fractures classified as Arbeitsgemeinschaft für Osteosynthesefragen (AO) subgroup 31-B (Müller et al. 1990), and by Pauwels (1935). Pertrochanteric fractures were defined as fractures classified as AO subgroup 31-A1 and 31-A2 (Müller et al. 1990), and by Jensen (1980a) and Kyle (1979). Subtrochanteric fractures were defined as fractures classified as AO subgroup 31-A3 and 32 (Müller et al. 1990), and by Seinsheimer (1978) and Zickel (1976). Complications were defined as revision surgery due to hardware failure, fracture collapse, nonunion, malunion, cut-out, or deep infection. Biomechanical studies included axial stiffness, torsional stiffness, and failure load. Stiffness is defined as force divided by displacement i.e. axial stiffness is the force (in Newtons) needed to bend the implant (in millimeters). Failure load is defined as the force needed to make the implant fail as defined by the individual paper.

Review of studies

Femoral neck fracture

2 biomechanical studies were included here (Table 1), and both showed that PF-LCP had higher axial stiffness. However, 1 study showed that the dynamic hip screw (DHS) had the highest failure load (Nowotarski et al. 2012) whereas the PF-LCP had the highest failure load in the other study (Aminian et al. 2007). Only 1 clinical study (Table 2) included femoral neck fracture and found a complication rate of 37% (Berkes et al. 2012).

Pertrochanteric fracture

No biomechanical studies were found here. 1 clinical study included only pertrochanteric fractures and 7 studies included both pertrochanteric fractures and subtrochanteric fractures (Table 2). The outcome varied markedly; 5 studies found complication rates of 25–53% (Wieser and Babst 2010, Floyd et al. 2013, Mardani-Kivi et al. 2013, Wirtz et al. 2013, Johnson et al. 2014). 1 study showed a combined low complication rate of 6% for pertrochanteric and subtrochanteric fractures (Chalise et al. 2012). The largest study, with 98 pertrochanteric fractures, reported a 2% reoperation rate, but it was not clearly defined as being prospective or retrospective (Zha et al. 2011). Finally, 1 study did not give any clear overall complication rate (Zhong et al. 2014).

Subtrochanteric fracture

5 biomechanical studies were included here. 2 used cadaveric bone and 3 used synthetic bone (Table 1). In the 2 studies that used cadaveric bone (Forward et al. 2012, Wang et al. 2014) PF-LCP had lower failure load than proximal femoral nail (PFN) and DHS. In the 3 studies that used synthetic bone (Crist et al. 2009, Floyd et al. 2009, Latifi et al. 2012), a PFN was not used for comparison and PF-LCP had higher failure load than an angled blade plate (ABP) in all 3 studies.

5 retrospective studies included only subtrochanteric fractures, and the complication rates varied from 3% to 43% (Table 2). 1 study was quasi-randomized, with a complication rate of 25% as compared to 35% in the DHS group (Dhamangaonkar et al. 2013). As stated above, both pertrochanteric and subtrochanteric fractures were often merged in a single study, and 3 of these studies (Wieser and Babst 2010, Zha et al. 2011, Johnson et al. 2014) had between complication rates of between 0% and 39% for subtrochanteric fractures.

Discussion

Even though the biomechanical studies showed equivalent or higher failure loads for femoral neck fracture, the results from the only clinical study (Berkes et al. 2012) were far worse—with a complication rate of 37%. This may not seem as high a complication rate as in meta-analysis results (Rogmark and Johnell 2006), but the patients of Berkes et al. (2012) were selected and compared to a historical cohort with a 9% complication rate.

Remarkably, there was no biomechanical study of pertrochanteric fracture. For the subtrochanteric fractures, PF-LCP had lower failure load than PFN, but higher than ABP. The reoperation rate for pertrochanteric and subtrochanteric fractures should be below 8% if compared to randomized controlled trials and large registry studies that use DHS or PFN (Parker and Handoll 2010, Matre et al. 2013a, 2013b, 2013c). However, only 4 studies on PF-LCP had complication rates below 8% and 9 studies had rates above this, having reoperation rates of between 15% and 53%.

We did not find any clear relation between the biomechanical studies and clinical studies. We can suggest several explanations for the disparities between biomechanical studies and clinical studies.

Biomechanical principle of internal fixation by LCP

The biomechanical principle of LCP combines compression techniques by using conventional holes, and bridging techniques by using threaded locking holes (Wagner 2003). This may allow an inherently rigid stabilization that should facilitate biological fixation through secondary bone healing due to callus formation (Miller and Goswami 2007). However, the rigid mechanical construction may be jeopardized by the quality of osteoporotic bone that cannot withstand the continuous stress, which subsequently results in microfracture—development of gaps between implant and bone with increasing micromotion. This may result in implant loosening and subsequently nonunion or failure of the implant (Wazen et al. 2013). In addition, historically, fractures in weight-bearing long bone have been found to be best treated by methods where compression and axial motion are tolerated (Parker and Handoll 2010). Thus, the LCP principle may be wrong in the treatment of standard proximal femoral fractures.

Clinical handling of the implant

Increasing options for application may mean technical challenges and increase the need for tutoring and training; otherwise, a long learning curve will increase the risk of failure (Bjorgul et al. 2011). Approximately 15 procedures are needed before a surgeon reaches a plateau for PFN (Altintas et al. 2014) and we suspect that the PF-LCP is technically more demanding. Moreover, proximal femoral fractures require acute surgery within 24 hours, which is often performed unsupervised by less experienced surgeons, which may increase the risk of complications with PF-LCP. In addition, we believe that introduction of more treatment options will increase the risk of failure overall.

Design of biomechanical studies

Biomechanical studies examine the response of a construct when force is applied; the results are then expressed in terms of force (Burstein and Frankel 1971). All studies try to take time into account by loading the implant dynamically to test alteration in the system over time. The amount of cycles resembles patient movement within the first couple of months after surgery. This contrasts with the longer duration of bone healing: up to 3–9 months. Some studies use only a few cycles and some use up to 90,000, which makes the studies incomparable (Crist et al. 2009, Forward et al. 2012). In addition, the biomechanical studies do not take into account that human bones are continuously remodeling and that microcracks may appear (Hazenberg et al. 2009). Thus, biomechanical methodology is based on the implication that a construct will ultimately break with the continuous loading of force. The clinical studies, on the other hand, include the time aspect as they report a percentage of failure over time. Finally, the biomechanical models often include synthetic bone of a quality different to that of osteoporotic bone. Thus, this represents the gap between biomechanical and clinical studies.

The gap between preclinical and clinical testing of new implants

According to the proposed stepwise methodology (Malchau et al. 2011), ex vivo studies should be an absolute necessity for future studies in vivo, as the initial step is preclinical testing followed by prospective randomized studies, multicenter studies, and registry studies. However, a few admissions are necessary regarding the initial step of preclinical testing. "The inherent gap" means that results from biomechanical studies are only snapshots of a process compared to clinical studies, which show the actual patient outcome. Also, the transparency of biomechanical studies can be challenging for people educated in the health system—as the vocabulary is in terms of physics. Knowledge in medicine, including orthopedic surgery and traumatology, tends to be cyclical and to develop with exponential progression (Lutter 2000). Consequently, grasping, reading, and understanding biomechanical studies requires a critical eye. It requires collaboration between research fields to better understand the results of and improvements in translational research, but still there will be a gap. This highlights the importance of proper clinical studies, to be conducted before widespread use of a new implant.

External validity of the present study

LCP gained immediate popularity after promising early reports (Sommer et al. 2003). A historical parallel to the PF-LCP is the sliding hip screw (SHS). Using a similar search strategy for DHS resulted in 88 biomechanical studies and several hundred clinical studies. The earliest biomechanical and clinical articles were published in 1980 and 1978 (Jensen et al. 1978, Jensen 1980b). The DHS is still used, and clinical studies with failure rates of around 3% are still being published. A long-term evaluation, as in the case of the DHS, is rare nowadays. The pace is high when marketing modern orthopedic implants. Implants are presented to the orthopedic community after—or at the same time as—biomechanical testing, leaving surgeons to perform the clinical survey in parallel to everyday use of the actual implant. Performing clinical trials is time-consuming. In the worst case, by the time that results from clinical studies with a high level of evidence are presented, the implant studied may already have been replaced with a new one (Carr 2005). We need to make conclusions about the performance of newly introduced implants before introducing new ones.

The question of evidence hierarchy and the clinical significance of biomechanical testing

It has been proposed that preclinical science, including biomechanical studies, may be regarded as part of the evidential hierarchy (Schemitsch et al. 2010). The evidence hierarchy has no universally accepted definition, but it can be explained as a reflection of the relative, empirical authority of various types of medical research. The empirical basis of biomechanical research gives value to the proposed idea of them as part of the evidential hierarchy. In addition to the empirical basis, a relation to the scientific problem is necessary for the applied research if it is to be considered to be part of the evidential hierarchy in this context.

We found that biomechanical studies have limited value in predicting clinical outcome of the PF-LCP. The biomechanical studies are concerned with how the PF-LCP fails and the clinical studies are concerned with how much it fails. The biomechanical studies are of no more value than to suggest candidates for clinical testing, if they fulfill test requirements.

The work in perspective

The biomechanical studies could not predict the clinical outcome of the LCP used for proximal hip fractures. Put in perspective, such biomechanical studies are inherently different from the clinical studies, as they examine the best possible theoretical use of the LCP without knowledge of the long-term outcome in a clinical setting. There is no doubt that they may have value when evaluating a new implant for fatigue failure or some similar problem. Properly designed clinical studies are mandatory when introducing new implants, and they cannot be replaced by biomechanical studies

No competing interest declared.

References

  • Altintas B, Biber R, Bail H J. The learning curve of proximal femoral nailing. Acta Orthop Traumatol Turc 2014; 48 (4): 396–400. [PubMed]
  • Aminian A, Gao F, Fedoriw W W, Zhang L Q, Kalainov D M, Merk B R. Vertically oriented femoral neck fractures: mechanical analysis of four fixation techniques. J Orthop Trauma 2007; 21 (8): 544–8. [PubMed]
  • Azboy I, Demirtas A, Gem M, Cakir I A, Tutak Y. A comparison of proximal femoral locking plate versus 95-degree angled blade plate in the treatment of reverse intertrochanteric fractures. Eklem Hastalik Cerrahisi 2014; 25 (1): 15–20. [PubMed]
  • Basso T, Klaksvik J, Syversen U, Foss O A. Biomechanical femoral neck fracture experiments–a narrative review. Injury 2012; 43 (10): 1633–9. [PubMed]
  • Berkes M B, Little M T, Lazaro L E, Cymerman R M, Helfet D L, Lorich D G. Catastrophic failure after open reduction internal fixation of femoral neck fractures with a novel locking plate implant. J Orthop Trauma 2012; 26 (10): e170–6. [PubMed]
  • Bjorgul K, Novicoff W M, Saleh K J. Learning curves in hip fracture surgery. Int Orthop 2011; 35 (1): 113–9. [PMC free article] [PubMed]
  • Burstein A H, Frankel V H. A standard test for laboratory animal bone. J Biomech 1971; 4 (2): 155–8. [PubMed]
  • Carr A J. Evidence-based orthopaedic surgery: what type of research will best improve clinical practice? J Bone Joint Surg Br 2005; 87 (12): 1593–4. [PubMed]
  • Chalise P K, Mishra A K, Shah S B, Adhikari V, Singh R P. Outcome of pertrochantric fracture of the femur treated with proximal femoral locking compression plate. Nepal Med Coll J 2012; 14 (4): 324–7. [PubMed]
  • Crist B D, Khalafi A, Hazelwood S J, Lee M A. A biomechanical comparison of locked plate fixation with percutaneous insertion capability versus the angled blade plate in a subtrochanteric fracture gap model. J Orthop Trauma 2009; 23 (9): 622–7. [PubMed]
  • Dhamangaonkar A C, Joshi D, Goregaonkar A B, Tawari A A. Proximal femoral locking plate versus dynamic hip screw for unstable intertrochanteric femoral fractures. J Orthop Surg (Hong Kong) 2013; 21 (3): 317–22. [PubMed]
  • Floyd J C, O’Toole R V, Stall A, Forward D P, Nabili M, Shillingburg D, et al. Biomechanical comparison of proximal locking plates and blade plates for the treatment of comminuted subtrochanteric femoral fractures. J Orthop Trauma 2009; 23 (9): 628–33. [PubMed]
  • Floyd M W, France J C, Hubbard D F. Early experience with the proximal femoral locking plate. Orthopedics 2013; 36 (12): e1488–94. [PubMed]
  • Forward D P, Doro C J, O’Toole R V, Kim H, Floyd J C, Sciadini M F, et al. A biomechanical comparison of a locking plate, a nail, and a 95 degrees angled blade plate for fixation of subtrochanteric femoral fractures. J Orthop Trauma 2012; 26 (6): 334–40. [PubMed]
  • Glassner P J, Tejwani N C. Failure of proximal femoral locking compression plate: a case series. J Orthop Trauma 2011; 25 (2): 76–83. [PubMed]
  • Gunadham U, Jampa J, Suntornsup S, Leewiriyaphun B. The outcome in early cases of treatment of subtrochanteric fractures with proximal femur locking compression plate. Malays Orthop J 2014; 8 (2): 22–8. [PMC free article] [PubMed]
  • Hazenberg J G, Hentunen T A, Heino T J, Kurata K, Lee T C, Taylor D. Microdamage detection and repair in bone: fracture mechanics, histology, cell biology. Technol Health Care 2009; 17 (1): 67–75. [PubMed]
  • Hu S J, Zhang S M, Yu G R. Treatment of femoral subtrochanteric fractures with proximal lateral femur locking plates. Acta Ortop Bras 2012; 20 (6): 329–33. [PMC free article] [PubMed]
  • Jensen J S. Classification of trochanteric fractures. Acta Orthop Scand 1980a; 51 (5): 803–10. [PubMed]
  • Jensen J S. Mechanical strength of sliding crew-plate hip implants. A biomechanical study of unstable trochanteric fractures. VI. Acta Orthop Scand 1980b; 51 (4): 625–32. [PubMed]
  • Jensen J S, Tondevold E, Mossing N. Unstable trochanteric fractures treated with the sliding screw-plate system. A biomechanical study of unstable trochanteric fractures. III. Acta Orthop Scand 1978; 49 (4): 392–7. [PubMed]
  • Johnson B, Stevenson J, Chamma R, Patel A, Rhee S J, Lever C, et al. Short-term follow-up of pertrochanteric fractures treated using the proximal femoral locking plate. J Orthop Trauma 2014; 28 (5): 283–7. [PubMed]
  • Kyle R F, Gustilo R B, Premer R F. Analysis of six hundred and twenty-two intertrochanteric hip fractures. J Bone Joint Surg Am 1979; 61 (2): 216–21. [PubMed]
  • Latifi M H, Ganthel K, Rukmanikanthan S, Mansor A, Kamarul T, Bilgen M. Prospects of implant with locking plate in fixation of subtrochanteric fracture: experimental demonstration of its potential benefits on synthetic femur model with supportive hierarchical nonlinear hyperelastic finite element analysis. Biomed Eng Online 2012; 11: 23. [PMC free article] [PubMed]
  • Lutter L D. Charlotte’s chocolate ice cream soda. Foot Ankle Int 2000; 21 (3): 181. [PubMed]
  • Malchau H. On the importance of stepwise introduction of new hip implant technology: assessment of total hip replacement using clinical evaluation, radiostereometry, digitised radiography and a national hip registry. In: Ortopedisk kirurgi On the importance of stepwise introduction of new hip implant technology: assessment of total hip replacement using clinical evaluation, radiostereometry, digitised radiography and a national hip registry. University of Gothenburg; 1995; Doctoral.
  • Malchau H, Bragdon C R, Muratoglu O K. The stepwise introduction of innovation into orthopedic surgery: the next level of dilemmas. J Arthroplasty 2011; 26 (6): 825–31. [PubMed]
  • Mardani-Kivi M, Mirbolook A, Khajeh Jahromi S, Rouhi Rad M. Fixation of intertrochanteric fractures: dynamic hip screw versus locking compression plate. Trauma Mon 2013; 18 (2): 67–70. [PMC free article] [PubMed]
  • Matre K, Havelin L I, Gjertsen J E, Espehaug B, Fevang J M. Intramedullary nails result in more reoperations than sliding hip screws in two-part intertrochanteric fractures. Clin Orthop Relat Res 2013a; 471 (4): 1379–86. [PMC free article] [PubMed]
  • Matre K, Havelin L I, Gjertsen J E, Vinje T, Espehaug B, Fevang J M. Sliding hip screw versus IM nail in reverse oblique trochanteric and subtrochanteric fractures. A study of 2716 patients in the Norwegian Hip Fracture Register. Injury 2013b; 44 (6): 735–42. [PubMed]
  • Matre K, Vinje T, Havelin L I, Gjertsen J E, Furnes O, Espehaug B, et al. TRIGEN INTERTAN intramedullary nail versus sliding hip screw: a prospective, randomized multicenter study on pain, function, and complications in 684 patients with an intertrochanteric or subtrochanteric fracture and one year of follow-up. J Bone Joint Surg Am 2013c; 95 (3): 200–8. [PubMed]
  • Miller D L, Goswami T. A review of locking compression plate biomechanics and their advantages as internal fixators in fracture healing. Clin Biomech (Bristol, Avon) 2007; 22 (10): 1049–62. [PubMed]
  • Moher D, Liberati A, Tetzlaff J, Altman D G. Preferred reporting items for systematic reviews and meta-analyses: the PRISMA statement. Int J Surg 2010; 8 (5): 336–41. [PubMed]
  • Müller M E, Nazarian S, Koch P, Schatzker J. The comprehensive classification of fractures of long bones. Springer-Verlag, Berlin: 1990.
  • Nowotarski P J, Ervin B, Weatherby B, Pettit J, Goulet R, Norris B. Biomechanical analysis of a novel femoral neck locking plate for treatment of vertical shear Pauwel’s type C femoral neck fractures. Injury 2012; 43 (6): 802–6. [PubMed]
  • Parker M. A new locking plate and dynamic screw sytem for internal fixation of intracapsular hip fractures; results for the first 200 patients treated. J Bone Joint Surg Br 2011; 93-B(SUPPII): 135.
  • Parker M J, Handoll H H. Gamma and other cephalocondylic intramedullary nails versus extramedullary implants for extracapsular hip fractures in adults. Cochrane Database Syst Rev 2010; (9): CD000093. [PubMed]
  • Pauwels F. Der Schenkelhalsbruch. Ein mechanisches Problem. Orthop Chir 1935; 63 (Beilagheft Z. Orthop. Chir. 63).
  • Rogmark C, Johnell O. Primary arthroplasty is better than internal fixation of displaced femoral neck fractures: a meta-analysis of 14 randomized studies with 2,289 patients. Acta Orthop 2006; 77 (3): 359–67. [PubMed]
  • Saini P, Kumar R, Shekhawat V, Joshi N, Bansal M, Kumar S. Biological fixation of comminuted subtrochanteric fractures with proximal femur locking compression plate. Injury 2013; 44 (2): 226–31. [PubMed]
  • Schemitsch E H, Bhandari M, Boden S D, Bourne R B, Bozic K J, Jacobs J J, et al. The evidence-based approach in bringing new orthopaedic devices to market. J Bone Joint Surg Am 2010; 92 (4): 1030–7. [PubMed]
  • Schmidt A H. Locked plating for subtrochanteric fractures: The next big thing. Tech in Orthop 2008; 23 (2): 106–12.
  • Seinsheimer F. Subtrochanteric fractures of the femur. J Bone Joint Surg Am 1978; 60 (3): 300–6. [PubMed]
  • Sommer C, Gautier E, Muller M, Helfet D L, Wagner M. First clinical results of the Locking Compression Plate (LCP). Injury 2003; 34Suppl2: B43–54. [PubMed]
  • Streubel P N, Moustoukas M J, Obremskey W T. Mechanical failure after locking plate fixation of unstable intertrochanteric femur fractures. J Orthop Trauma 2013; 27 (1): 22–8. [PubMed]
  • Wagner M. General principles for the clinical use of the LCP. Injury 2003; 34Suppl2: B31–42. [PubMed]
  • Wagner M, Frenk A, Frigg R. New concepts for bone fracture treatment and the Locking Compression Plate. Surg Technol Int 2004; 12: 271–7. [PubMed]
  • Wang J, Ma X L, Ma J X, Xing D, Yang Y, Zhu S W, et al. Biomechanical analysis of four types of internal fixation in subtrochanteric fracture models. Orthop Surg 2014; 6 (2): 128–36. [PubMed]
  • Wazen R M, Currey J A, Guo H, Brunski J B, Helms J A, Nanci A. Micromotion-induced strain fields influence early stages of repair at bone-implant interfaces. Acta Biomater 2013; 9 (5): 6663–74. [PMC free article] [PubMed]
  • Wieser K, Babst R. Fixation failure of the LCP proximal femoral plate 4.5/5.0 in patients with missing posteromedial support in unstable per-, inter-, and subtrochanteric fractures of the proximal femur. Arch Orthop Trauma Surg 2010; 130 (10): 1281–7. [PubMed]
  • Wirtz C, Abbassi F, Evangelopoulos D S, Kohl S, Siebenrock K A, Kruger A. High failure rate of trochanteric fracture osteosynthesis with proximal femoral locking compression plate. Injury 2013; 44 (6): 751–6. [PubMed]
  • Zha G C, Chen Z L, Qi X B, Sun J Y. Treatment of pertrochanteric fractures with a proximal femur locking compression plate. Injury 2011; 42 (11): 1294–9. [PubMed]
  • Zhong B, Zhang Y, Zhang C, Luo C F. A comparison of proximal femoral locking compression plates with dynamic hip screws in extracapsular femoral fractures. Orthop Traumatol Surg Res 2014; 100 (6): 663–8. [PubMed]
  • Zickel R E. An intramedullary fixation device for the proximal part of the femur. Nine years’ experience. J Bone Joint Surg Am 1976; 58 (6): 866–72. [PubMed]

Articles from Acta Orthopaedica are provided here courtesy of Taylor & Francis